1.用介词或介词短语表示虚拟条件

常用的介词或介词短语主要有without（没有），but for（要不是），in the absence of（如果没有）或were it not for（要是没有），but that（假设……不）等。例如：Without electricity, there would not be modern industry.

But for the leadership of the Party, we couldn’t live such a happy life.

In the absence of gravity, there would be no air around the earth.

Example:

Without gravity, we ______ able to walk.

a. were b. should be c. can be d. should not be

Were it not for the atmosphere, the stars ______ shining at any time in the day.

a. be seen b. can be seen

c. could be seen d. could have been seen

2.用动词不定式表示虚拟条件

It would be a shame to stop our work half-way.

It would take about 125 million of molecules of water to form a row an inch long.

如果要排成一寸长就需要大约一亿二千五百万个水分子。

Example:

It ______ better to think independently.

a. goes b. looks c. would be d. shall be

3.通过上下文表示虚拟条件

常用的连接词有or, otherwise, but等。例如：

I was very busy yesterday. Otherwise I would have come to see you.

The worn parts have been replaced at the proper time, or a damage might have happened.

磨损的部件及时更换了，否则就会发生破坏。虚拟语气的其它表达形式

Example:

He went on foot, but he ______ by bus.

a. might go b. should be gone

c. could have gone d. ought have gone

The traffic was very heavy; otherwise I ______ here 50 minutes sooner.

a. would have been b. would be

c. should be d. had been

4.虚拟语气用在…would(或had)rather（或would just as soon）+ 从句的句式中，表示与事实相反的愿望。从句谓语动词要用过去式。例如：

I would rather you stayed here.

I would rather that you didn’t do anything.

I’d just as soon you didn’t go there.

Example:

I’d just as soon ______ those important papers with you.

a. that you won’t take b. your not taking

c. please don’t you take d. you didn’t take

I’d rather you ______ anything about it for the time being.

a. do b. didn’t do c. don’t d. didn’t